A brake assembly of this type is generally fashioned such that it is actuated by means of either a spring or fluid pressure and is disactuated by means of either fluid pressure or a spring. In the past, a fluid cylinder mechanism for actuating or disactuating the brake has generally been provided by utilizing a wall of vehicle as shown, for example, in JP, A(U) No.55-52424, JP, A (U) No. 58-17220, JP, A(P) No. 60-179550 and JP, Y2 No. 62-3306.
The structure according to this prior art is advantageous in that a fluid cylinder formed in a vehicle wall eliminates cost for providing a separate fluid cylinder and in that space for the cylinder is saved. However, this structure does not permit a pre-assemblage of a brake assembly, having a considerable number of parts, at the outside of a vehicle. Consequently, assemblage of a brake assembly is considerably troublesome so that its manufacturing cost is heightened.